1. Statement of the Technical Field
The invention concerns image processing, and more particularly, systems and methods for processing remotely acquired imagery.
2. Description of the Related Art
Some satellite imagery tools are commercially available for characterizing atmospheric conditions and for determining the impact of such conditions on the images obtained. However, such tools typically require specialized data. For example, hyperspectral imaging (>100 bands) is typically used for atmospheric characterization, as it typically includes long-wave IR thermal imagery. The IR imagery is then generally used to determine how the location imaged was illuminated by the sun and sky, and how reflected light was being attenuated by the atmosphere. Therefore, based on this data, surface reflectance for the images can be adjusted to enhance final satellite images.
However, when multi-spectral imagery (˜4 bands) is used, only reflected visible and near-infrared imagery is typically collected and cannot be generally used for atmospheric characterization. For such imagery, atmospheric conditions in satellite imaging tools are typically derived from the meta-data associated with imagery (i.e., collection date, collection time, sensor position, and coordinates of location imaged). As a result, even commercially available atmospheric modeling tools, such as FLAASH (Fast Line-of-sight Atmospheric Analysis of Spectral Hypercubes) developed by Spectral Sciences Inc., typically default to a generic atmospheric model when used for enhancing non-hyperspectral imagery.
Unfortunately, the generic models used with multi-spectral imagery are generally limited to only capturing and modeling the effects of common gases. That is, generic models typically account only for a fixed number of gases and effects in the atmosphere. Therefore, these generic models often fail to capture or properly model the impact due to other atmospheric effects and gases, such aerosol loading or haze. As a result, when a generic model is used to derive atmospheric effects for adjusting multi-spectral imagery, the lack of proper modeling of these other effects can result in improperly adjusted imagery.